Already known, notably through the French patent applications 2 812 235 and 2 873 617, is such a press which comprises:                a cage presenting a cylindrical lateral wall and two flanges closing said cage respectively at one end and at the other end of said lateral wall;        means of mounting said cage to rotate about its axis in a position where the latter is positioned horizontally, comprising a chassis;        means for selectively controlling the rotation of said cage about its axis;        a deformable flexible membrane positioned in said cage, fixed in a seal-tight manner to the lateral wall of the cage along two opposite longitudinal edges and fixed in a seal-tight manner to the flanges along two respective transversal edges each situated between an end of one longitudinal edge and an end of the other longitudinal edge so that said membrane separates the internal volume of said cage into a pressing chamber delimited by said membrane, by a first half of said lateral wall situated between said two opposite longitudinal edges and by a first half of each of said flanges situated, relative to the respective transversal edges, on the side of the first half of the lateral wall, and into a control chamber delimited by said membrane, by the second half of said lateral wall and by the second half of said flanges, said flexible membrane, at rest, having almost the form of half of the cage;        means of admitting a pressure agent into said control chamber and means of sucking said pressure agent out of said control chamber;        at least one door blocking or revealing an opening provided in said first half of the lateral wall of the cage;        drainage means equipping said first half of the lateral wall of the cage; and        means of recovering said liquid part of the matter leaving the pressing chamber via said drainage means.        
Before filling the pressing chamber with matter such as the grape harvest, means of sucking the pressure agent out of the control chamber are actuated, so that a vacuum is produced therein and the membrane is against the second half of the lateral wall and the flanges of the cage.
To produce the pressing, once filling is complete, means of admitting a pressure agent into the control chamber are actuated, so that the matter that is present therein is applied against the drainage means and pressurized, with the result that the liquid part of this matter flows through the drainage means. In general, several phases of pressing the matter such as grape harvest are carried out, the pressing phases being separated by press-cake breaking-up phases in which the cage is rotated about its axis to dislodge the cake of matter that is formed under the effect of the pressure.
To empty the cage once the pressing is complete, the door is opened and the cage rotated so that the solid part remaining in the pressing chamber is gradually evacuated through the orifice revealed by the door.
To avoid damaging the membrane, the vacuum is formed in the control chamber in the press-cake breaking-up phase and in the emptying phase.